The present invention relates to stable, anaerobically-hardening adhesive systems based on polymerizable methacrylates and acrylates that are free of peroxides and hydroperoxides, are stable in storage, harden at an accelerated rate under anaerobic conditions and are suitable for bonding and sealing, particularly of metal surfaces.
A process is known for the preparation of adhesives based on methacrylates that are stable in storage, by heating the monomer ester with a chelating agent, benzoic acid sulfimide and a tertiary amine in the presence of an inhibitor, until the content of active oxygen is at least 25 ppm. While the process does not require constant passing of gaseous oxygen through the adhesive during its preparation, relatively long periods of time are necessary to produce suitable mixtures. Also possible is the preparation of anaerobically hardening mixtures based on methacrylates with the use of .alpha.-aminosulfones, but only the addition of dialkyl peroxides results in technically useful mixtures.